The present invention relates to a freight car truck, and in particular to a side frame pedestal area where the axle and bearing are journaled to the side frame.
Application Ser. No. 08/084,286, filed Jun. 28, 1993, now U.S. Pat. No. 5,404,926 and assigned to the assignee of the present invention, discloses a special type of bearing adapter which is designed to permit lateral movement between each axle and the corresponding side frames. FIG. 1 of the foregoing patent application shows a truck assembly 10 including a pair of axles 12 and 14, a pair of side frames 16 and 18, four wheels 20, 22, 24 and 26, and a bolster 28 which extends laterally between the side frames with its opposed ends projecting into openings in the side frames so as to be supported on spring assemblies shown at 30. The truck assembly 10 further includes four bearings 32, each having an adapter assembly 34 disposed between the bearing and the underside of a pedestal portion 36 of the side frame.
Still referring to the above-identified patent application, FIG. 2 shows one of the pedestal portions 36 of the side frame, each side frame having one such pedestal portion 36 at each end thereof to receive in the pedestal opening a bearing 32. The adapter 34 and related components are disposed between the top of the bearing 32 and the underside of the pedestal roof, the latter being shown at 40 in FIGS. 4 and 5 in the prior application. FIGS. 4 and 5 further show a pair of side walls 42 and 44 which define a pedestal opening 46. In addition, on each of the side walls 42 and 44, near the upper ends thereof, a thrust lug 48 is formed.
As shown in the prior application in FIG. 3, the adapter 34 has depending end flanges 65 which extend down over a portion of the bearing 32 to prevent significant lateral or axial movement between the adapter 34 and the axle 12, the axle being fixed relative to the wheels. In accordance with the invention disclosed in the foregoing application, relative lateral or axial movement, left and right movement as shown in FIG. 3, is permitted between the adapter 34, axle 12 and wheels on the one hand, and the side frames 16 and 18. The uppermost structure in FIG. 3 comprises the pedestal portion 36 of the side frame 16, and about 3/4 inch of lateral or axial movement between that side frame and the adapter 34 and related components is a feature of the invention of the pending application.
Reference is now made to FIG. 4 of the above-identified application for an explanation of the physical structure which permits and limits the magnitude of such relative lateral movement. FIG. 4 shows a portion of one of the opposed thrust lugs 48 formed near the top of the pedestal opening 46 on the side frame 16. The two thrust lugs 48 are best shown in FIG. 5. With reference to FIG. 4, when the components are assembled, the thrust lugs 48 fit down into openings 66 in each side of the adapter, such openings being defined by opposed shoulders 68 and 70.
In a conventional truck assembly, the width or axial dimension of the thrust lugs 48 is only slightly less than the width or axial dimension of the thrust lug opening 66 formed in the adapter as shown in FIG. 4, with the result that no meaningful relative lateral movement is permitted. In accordance with the invention disclosed in the aforesaid pending application, the width or axial dimension of the side frames 16 and 18 and thrust lugs 48 is not reduced, but is standard. Instead, the width or axial dimension of the thrust lug opening 66 in FIG. 4 has been increased by 3/4 inch, making it a total of 4 and 13/16th inches. As a result, a total of approximately 3/4 inch of relative lateral movement is permitted between the side frame 16 and the adapters 34. Further relative lateral movement is not permitted as the thrust lugs 48 on the side frame will engage the shoulders 68 and 70 which define the thrust lug opening 66 in each of the two sides of the adapter 34 as shown in FIG. 4.
By permitting up to approximately 3/4 inch lateral movement between the wheel and axle assembly and the side frame, as taught by the above-identified patent application, it is possible to achieve improved ride conditions and to reduce truck hunting which is a swiveling action of the truck while running down the track. At the same time, such relative lateral movement of the truck components increases wear and can require replacement of worn parts. The present invention is intended for use on freight car trucks, as for example trucks used with coal cars, where the quality of the ride is not the primary factor. In such cases, it is desired to sacrifice to some extent the quality of the ride in order to minimize wear.
By substantially eliminating relative lateral movement between an adapter and the side frame, it is possible to significantly reduce wear between the parts. However, prior to the invention of the above-identified pending application, it was known to provide railway trucks which did not permit significant relative lateral movement between the side frame and the components mounted in the pedestal opening of the side frame. The present invention not only eliminates such relative lateral movement, but at the same time it provides important advantages not afforded by known arrangements. Indeed, it significantly reduces forces between the wheel flanges and the rails to improve the negotiation of curves in the track.
The present invention does not utilize a standard adapter. Instead, it utilizes an adapter of the type disclosed in the aforesaid pending application where the space between the shoulders shown at 68 and 70 in FIG. 4 is a total of approximately 4 and 13/16th inches, or approximately 3/4 inch greater than standard, i.e., approximately 3/4 inch greater than the lateral width of the conventional thrust lugs as shown as 48 in FIGS. 4 and 5 of the foregoing application. However, in accordance with the present invention, that increased space between the adapter shoulders is not utilized to achieve relative lateral movement, but instead is used to accommodate a special adapter pad which is positioned between the adapter and the side frame and eliminates metal-to-metal contact between those two components.
In accordance with the present invention, the adapter pad is non-metallic, and is preferably a polyurethane elastomer having a hardness in the range of 70A to 75D. Other materials such as rubber can be used, but a castable polyurethane or castable polymer is preferred. Of course, any railcar truck utilizing adapters of the type described in the aforesaid application, having about 3/4 inch extra space between the shoulders 68 and 70 of the adapter, may be converted for use in accordance with the present invention by adding an adapter pad as taught by the present invention. The addition of such an adapter pad will eliminate the relative lateral movement described in the prior application, it will reduce wear, and at the same time it will markedly improve the action between the wheels and the rail to achieve advantages not afforded by the invention of the prior application.
The foregoing and other objectings and advantages of the invention will be apparent from the following description of certain preferred embodiments thereof, taken in conjunction with the accompanying drawings.